Heel tightener for ski bindings



July 30, 1968 H. SCHEIB HEEL TIGHTENER FOR SKI BINDINGS 2 Sheets-Sheet 1 Filed March 18, 1966 INVENTOR.

HERMANN SCHEIB July 30, 1968 Filed March 18, -l966 H. SCHEIB HEEL TIGHTENER FOR SKI BINDINGS 2 Sheets-Sheet 2 INVENTOR.

HERMANN SCHEIB United States Patent 65,799 2 Claims. (Cl. 280-1135) ABSTRACT OF THE DISCLOSURE A heel tightener for ski bindings comprising two tensile elements, which extend along opposite sides of the heel of the boot, means securing said tensile elements to the ski, a forwardly open, three-sided frame member, which extends behind the heel approximately in the direction of the tensile elements and upon which said tensile elements bear, and a pusher, which fits the opening of the frame member comprising a rear part mounted in the frame member close to its rear end for pivotal movement about an axis which is transverse to the ski and parallel to the surface of the ski, a forward part engageable in the heel groove, and a spring biasing said parts in the direction of said tensile elements, said pusher being pivotally movable out of the frame member in an upward direction to a large extent whereas in its clamping position it is approximately parallel to the frame member and engages an abutment on the frame member, which abutment prevents a downward pivotal movement of the pusher out of the frame member, said pusher being adapted to be locked in its clamping position, said spring element being a gas spring having an approximately constant spring rate.

The copending application Ser. No. 532,742, filed Mar. 8, 1966, relates to a heel tightener for ski bindings, in which two tensile elements, which extend along opposite sides of the heel of the bootand are directly or indirectly secured to the ski, bear on a forwardly open, three-sided frame member, which extends behind the heel approximately in the direction of the tensile element, and a pusher, which fits the opening of the frame member, is mounted in the latter close'to its rear end for pivotal movement about an axis which is transverse to the ski and parallel to the surface of the ski, the forward end of said pusher being engageable in the heel groove, said pusher being pivotally movable out of the frame member in an upward direction to a large extent whereas in its clamping position it is approximately parallel to the frame member and engages an abutment on the frame member, which abutment prevents a downward pivotal movement of the pusher out of the frame member, said pusher being adapted to be locked in its clamping position, at least one spring, which acts generally in the direction of the tensile elements, being provided between the forward end of the pusher and the means whereby the tensile elements are secured to the ski.

The present invention relates to a further improvement of the heel tightener disclosed in the above-mentioned co-pending application and resides in the use of a gas spring known per se, as a spring element, which is preferably combined with a heel-engaging element to form the pusher.

The gas spring is a cylinder, which contains a gas under pressure and in which a piston is slidably mounted, which piston is provided with a piston rod only at one end, the gas spring cylinder being sealed at one end about the piston rod. To prevent an additional unilateral compression during a displacement of the piston in the cylinder, the pis- "ice ton is formed with ducts, which enable an equalization of pressure between the chambers on both sides of the piston. As the piston rod is secured only to one end of the piston, the end faces of the piston have different areas. One of these faces is larger by the cross-sectional area of the piston rod so that a force which corresponds to the product of the pressure and the cross-sectional area of the piston rod acts on the piston from this end and must be overcome to displace the piston. This force ensures also an automatic restoring of the piston. As the pressure in the cylinder remains almost constantonly a slight change in pressure can be effected when the piston rod is entering the cylinder-this arrangement constitutes a spring which has an almost constant spring rate. In any position, a displacement of the piston is opposed by an approximately constant force.

In this embodiment too, the arrangement of the pivotal axis for the pusher at the rear end of the frame member has the result that it is sufficient to engage the heel groove with the forward end of the pusher, which has been swung upwardly out of the frame member, whereafter the rear cross-bar of the frame member is gripped and pulled upwardly until the clamping position has been reached. In this operation the heel-engaging member, which is combined with the gas spring to form the pusher and which is suitably connected to the piston rod of the gas spring, is urged toward the gas spring cylinder so that the force of the gas spring bears on the skiing boot and applies the desired pushing force.

As has already been described in the main patent, it is particularly suitable if a locking of the heel tightener can be locked by a downward pivotal movement of the pusher from its position parallel to the frame member through a small angle, which amounts preferably to about 5, until the pusher engages the abutment provided on the frame member. In this case the locking is effected by a pivotal movement of the pusher through its dead center position, behind which the pusher engages the abutment. A safety release action to release the foot may be effected, e.g., in that the piston and the piston rod are pushed toward the gas spring cylinder by means of the heelengaging member, which runs up on a bevelled surface in such a manner that the pusher is raised beyond its dead center position so that the foot is released immediately.

The invention will be explained more fully hereinafter with reference to the accompanying drawing.

In the drawing,

FIG. 1 is a sectional view showing a gas spring.

FIG. 2 is a top plan view showing another heel tightener according to the invention.

FIG. 3 shows the heel tightener assembly of FIG. 2 in clamping position.

FIG. 4 is a side elevation showing the heel tightener assembly of FIG. 2 before engagement with the heel groove of the skiing boot.

With reference to FIG. 1, the mode of operation of the gas spring will be explained once more. The gas spring consists of the gas cylinder 1, the piston 2 and the piston rod 3. A sealing system 6 serves for guiding the piston rod 3 and seals the cylinder 1 about the piston rod. The cylinder 1 contains a gas underpressure. Owing to the bores 7, 8 in the piston, the gas'pressure acts on both ends of the piston 2. As the piston faces 9 and 10 differ in area, the face 9 being larger by the cross-sectional area of the piston rod, a force equal to the cross-sectional area of the piston rod times pressure acts at any time in the direction of the arrow. This force tends to urge the piston toward its upper dead center position at the sealing system 6. When the piston rod 3 and the piston 2 are urged into the cylinder 1, the above-mentioned force must be overcome and remains almost constant as the ducts 7, 8 enable an immediate equalization of pressure between the chambers 4, which are formed by such movement. This arrangement prevents an additional unilateral compression. A small change of the pressure within the cyl inder 1 is due to the change in volume resulting from the introduction of the piston rod 3 into the cylinder. This change in pressure may be kept very small.

If the ducts 7, 8 are very small, the effect which is obtained is surprising, particularly in a heel tightener assembly. When a relatively fast displacement of the piston is effected in this case, the gas cannot yield entirely into the other chamber during the time which is available so that an additional unilateral compression results and a higher opposing force must be overcome. The pressure cannot be equalized unless the piston is maintained in a displaced position for a somewhat longer time. If such a spring is used in a heel tightener assembly, the short-time, sudden lifting forces which arise during normal skiing are opposed by a stronger spring force so that the boot is properly held down on the ski. Only when forces acting at right angles to the surface of the ski are maintained for a somewhat longer time, as is the case during a forward fall, can the unilateral overpressure be relieved so that the opposing spring force is reduced. As a result, the static spring forces which are required are much smaller than normally so that the danger of an injury of the skier is much reduced.

FIGS. 2 to 4 show a heel tightener according to the invention with a gas spring as spring element. The two tensile elements 11, 12 consist of wire cables and are connected to the ski rigidly or for an adjustment in the longitudinal direction of the ski. This is known per se and need not be described in detail. At the other end, the tension elements are supported in the limbs 14, 15 of the frame member 13. The two limbs 14, 15 of the frame member 13 are connected by a cross-bar 16. A shaft 17 is provided almost on the level of the cross-bar 16 and serves for a pivotal mounting of the pusher, which consists of the gas spring 1, the piston rod 3 of said spring and the heel-engaging member 18, in the frame member 13.

To close the heel tightener, the pusher is moved to the position shown in FIG. 4 and its heel-engaging member 18 is engaged in the heel groove 21. Now the cross-bar 16 can be pulled upwardly so that the heel tightener can be moved without a large effort into its clamping position, which is shown in FIG. 3 and in which the pusher is locked because it has moved beyond its dead center position. During this movement, the heel-engaging member 18 and the piston rod 3 are urged toward the gas spring cylinder 1 so that the opposing pressure exerted by the gas spring forces the boot 22 against the toe iron of the ski binding. This toe iron is not shown. To prevent a downward pivotalmovement of the pusher out of the locking position, the frame member 13 is provided with a stop 19. The heel tightener can also be opened in a simple manner and without a great effort as a relatively large effort arm is avaiable when the heel tightener is to be opened and restored to its position shown in FIG. 4 by downward pressure applied to the cross-bar 16.

For a release action in response to an excessively strong tension, as arises during a fall of the skier, the heel-engaging member 18 and the piston rod 3 are urged toward the gas spring cylinder 1 in this embodiment. This causes the heel-engaging member 18 to run up on an oblique surface 20 of the stop 19 so that the frame member is moved about the pivot 17 below its dead center position and the foot is immediately released.

What is claimed is:

1. A heel tightener for ski bindings comprising two tensile elements, which extend along opposite sides of the heel of the boot, means securing said tensile elements to the ski, a forwardly open, three-sided frame member, which extends behind the heel approximately in the direction of the tensile elements and upon which said tensile elements bear, and a pusher, which fits the opening of the frame member comprising a rear part mounted in the frame member close to its rear end for pivotal movement about an axis which is transverse to the ski and parallel to the surface of the ski, a forward part engageable in the heel groove, and a spring biasing said parts in the direction of said tensile elements, said pusher being pivotally movable out of the frame member in an upward direction to a large extent whereas in its clamping position it is approximately parallel to the frame member and engages an abutment on the frame member, which abutment prevents a downward pivotal movement of the pusher out of the frame member, said pusher being adapted to be locked in its clamping position, said spring ele ment being a gas spring having an approximately constant spring rate.

2. A heel tightener according to claim 1 wherein the forward part of the pusher includes a heel-engaging member which is connected to the piston rod of the gas spring.

References Cited UNITED STATES PATENTS 168,980 10/ 1875 Giffard 267- 3,055,673 9/1962 Marker 28011.35 3,190,635 6/ 1965 Wustenhagen et al. 267-65 3,249,365 5/1966 Beyl 280-1135 3,305,242 2/ 1967 Marker 280-1135 FOREIGN PATENTS 1,110,856 10/1955 France. 1,190,118 3/1959 France.

BENJAMIN HERSH, Primary Examiner. MILTON L. SMITH, Assistant Examiner. 

